Evaluation of Modulus of Elasticity, Mineral Composition and Bone Mineral Density of Trabecular Bone L3- Vertebrae Sampl
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Evaluation of Modulus of Elasticity, Mineral Composition and Bone Mineral Density of Trabecular Bone L3- Vertebrae Samples Extracted From Mexican Men R. Valdés1, A. L. Solis3, F .A. Godínez1, E. Martínez4, C.H. Villegas3, M. Navarrete1 1
Instituto de Ingeniería; Universidad Nacional Autónoma de México; Av. Universidad 3000, C.P.04510, D.F. México, [email protected] 3 Laboratorio Morfología celular y molecular, 4Servicio de Tomografía; Instituto Nacional de Rehabilitación; Calzada México Xochimilco No. 289, C.P. 14389, D.F. México. ABSTRACT Extracted samples of L3 vertebrae, the healthy, osteopenic and osteoporotic from Mexican men, were fixed to carry out measurements of the modulus of elasticity (ME) and the minerals content, on the trabecular zone to study their behavior as a function of age. To determine the ME the immersion ultrasonic method (IUM) was used, X-ray dispersion was applied to know the chemical element concentration (Ca++, Na++, P, and Mg++) and computerized axial tomography (CAT) to obtain bone mineral density (BMD).The samples were organized in four groups by decade. The samples in the range of 30-39 years revealed: a normal BMD and a concentration [% w/w] between pairs of Ca++/P, Ca++ /Mg++, P/Mg++ and Mg++/ Na ++ with correlation positive due to the strong dependence between them. The average ME results were: 2.79±0.326, 2.68±0.45, 2.66±0.43 and 2.70±0.397 [GPa] for each decade respectively. The ME profiles show a nonlinear behavior as a function of age, indicating a minimum value in the third decade, similar behavior is observed in the Ca++. An exponential behavior between ME and T-score was obtained. The plotted Ca++ and ME as a function of area showed a homogeneous distribution for the first and a non homogeneous for the second. INTRODUCTION Mexico is facing an increase in osteoporosis cases due to the growing number elderly population and an increase in life expectancy [1]. Osteoporosis and fragility fractures have recently become a focus of research in Mexico, where, the prevalence of vertebral fractures in the population 50 years of age and older was found to be 19.5 % for women and 9.6 % for men [3, 4]. In the lumbar vertebrae, the loss of bone volume (53 %) is more evident than in thoracic (41 %) and cervical samples (24 %) in men of 30 to 80 years of age. [8]. Recent studies have shown that minerals contribute to bone stiffness [5]. Additionally, it was found that osteoporosis is not a simple loss of the bone mass, but that it also involves significant changes in the biochemical and physical properties of bones [6]. Trabecular bone is a highly complex material. The actual elastic modulus of trabecular bone has been measured over the last century in the range of 1-14 [GPa] [7]. The variation in the ME is dependent of many factors, including anatomic site, age and health condition. Fourteen samples of trabecular bone from L3-vertebra were analyzed: 3 healthy, 3 with osteopenia and 8 of them osteoporotic. The analysis was made in vitro using dual-energy X-ray absorptiometry (DXA), co
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